Motor

Abstract

The present invention provides a novel motor in which a decrease in efficiency can be suppressed.　This motor (30) is provided with a rare earth magnet (10). The rare earth magnet (10) has a plurality of magnets (11) and an insulating layer (13) present between the plurality of magnets (11). The insulating layer (13) contains an inorganic crystal as a main component.

Description

motor

[0001] This disclosure relates to a motor. This application is based on and claims the benefit of priority from Japanese Patent Application No. 2023-146628 filed on September 11, 2023, and Japanese Patent Application No. 2023-146627 filed on September 11, 2023, the entire contents of which are incorporated herein by reference.

[0002] Patent Document 1 discloses a rotor equipped with a permanent magnet. Patent Document 2 also discloses a rotor equipped with a permanent magnet. In both cases, the permanent magnet is a block-shaped magnet that is not divided. Patent Document 3 discloses an IPM rotor equipped with a magnet. As an example of the magnet, an example is described in which the magnet is composed of multiple segmented magnets divided in the axial direction.

[0003] JP 2022-155164 A JP 2022-155204 A JP 2018-161001 A

[0004] In recent years, there have been various demands for motors. For example, there is a desire to suppress a decrease in motor efficiency by using magnets that can reduce eddy current loss that occurs inside the motor in high-temperature environments such as 150°C. The present disclosure has been made in consideration of the above circumstances, and aims to provide a new motor that can suppress a decrease in efficiency. The present disclosure can be realized in the following forms.

[0005] A motor including a laminated magnet, wherein the laminated magnet has a plurality of magnets and an insulating layer present between the plurality of magnets, and the insulating layer is primarily composed of inorganic crystals.

[0006] According to the present disclosure, a novel motor capable of suppressing a decrease in efficiency can be provided.

[0007] 13A and 13B are perspective views schematically showing an example of a rare earth magnet according to the first embodiment. A top view of a rare earth magnet. A cross-sectional view taken along line A-A in FIG. 2. A diagram for explaining a method for measuring the average degree of orientation of a magnet. A cross-sectional view of Alternative Example 1 of a rare earth magnet. An enlarged view showing an enlarged portion of FIG. 5. A perspective view schematically showing Alternative Example 2 of a rare earth magnet. A diagram for explaining a method for measuring the average degree of orientation of the magnet in Alternative Example 2. A diagram schematically showing each part for measuring the average degree of orientation. A cross-sectional view schematically showing a part of a motor. A plan view of a rotor. A perspective view schematically showing an example of a laminated magnet according to the second embodiment. A top view of a laminated magnet. A cross-sectional view taken along line A-A in FIG. 13. A cross-sectional view of Alternative Example 1 of a laminated magnet. A diagram for explaining a method for measuring the average degree of orientation of a magnet. A diagram for explaining a method for measuring the average degree of orientation of the magnet in Alternative Example 2. A diagram schematically showing each part for measuring the average degree of orientation. A cross-sectional view schematically showing a part of a motor. A plan view of a rotor. 10A and 10B are diagrams showing simulation results of sample B and an image of magnetic flux density distribution, respectively, and simulation results of sample C and 10C are diagrams showing simulation results of sample B and an image of magnetic flux density distribution, respectively, and

[0008] The present disclosure also aims to provide a new motor with improved performance using magnets that can reduce eddy current loss generated inside and can concentrate magnetic flux.

[0009] Here are some desirable examples of the present disclosure. [1] A motor including a laminated magnet, wherein the laminated magnet has a plurality of magnets and an insulating layer between the plurality of magnets, and the insulating layer is primarily composed of inorganic crystals. [2] The motor described in [1], wherein the laminated magnet has the plurality of magnets and the insulating layer stacked in a first direction, the magnet contains a rare earth element, and has a curved shape that is convex in a second direction when viewed from the first direction, and the average degree of orientation of each 1 mm wide portion centered on a normal line at multiple points on the curve on the convex side in the second direction from one end to the other of the outer periphery of the magnet when viewed from the first direction is 90% or more. [3] The motor described in [1] or [2], which is used at a maximum rotational speed of 7,500 rpm or more.

[0010] <<First Embodiment>> A first embodiment of the present disclosure will be described in detail below. Note that in the first embodiment, when a numerical range is indicated using "-", it is assumed that both the lower limit and the upper limit are included unless otherwise specified. For example, the expression "10-20" includes both the lower limit "10" and the upper limit "20". In other words, "10-20" has the same meaning as "10 or more and 20 or less". Furthermore, in this specification, the upper and lower limit values ​​of each numerical range can be arbitrarily combined. Hereinafter, the Z-axis direction in each figure is the direction in which the multiple magnets 11 are arranged. One direction perpendicular to the Z-axis direction is the X-axis direction (also referred to as the horizontal direction), and the direction perpendicular to the Z-axis direction and the X-axis direction is the Y-axis direction (also referred to as the vertical direction).

[0011] 1. Motor 30 The motor 30 includes a rare earth magnet 10 (laminated magnet). The rare earth magnet 10 has a plurality of magnets 11 and insulating layers 13 present between the plurality of magnets 11. The insulating layers 13 are primarily composed of inorganic crystals.

[0012] The rare earth magnet 10 of the present disclosure has low eddy current loss generated internally and is resistant to change, which can contribute to one or more of the following effects: motor miniaturization, suppression of heat generation, improved heat resistance, and improved heat dissipation. Furthermore, compared to insulating layers made of resin or the like, the insulating performance of the insulating layer 13 of the rare earth magnet 10 is less susceptible to changes due to humidity, temperature, and deterioration over time, which can suppress performance degradation of the motor 30.

[0013] An example of a motor 30 equipped with a rare earth magnet 10 will be described below with reference to FIGS. 10 and 11 . The motor 30 includes a stator 31 and a rotor 33 arranged inside the stator 31. A rare earth magnet 10 is arranged in the rotor 33, and a winding (not shown) is arranged in the stator 31. The motor 30 in FIG. 10 is an inner rotor type in which the magnet is arranged on the inside (rotating shaft side) and the winding is arranged on the outside. The motor is not limited to the inner rotor type. For example, the motor may be an outer rotor type in which the winding is arranged on the inside (rotating shaft side) and the magnet is arranged on the outside.

[0014] The rotor 33 includes a rotating shaft 34, a rotating core 35, and a plurality of rare earth magnets 10. The rotating core 35 is formed by laminating electromagnetic steel sheets. A shaft hole 37 is formed in the center of the rotating core 35. The rotating shaft 34 is inserted into the shaft hole 37. A plurality of magnet holes 39 are formed in the rotating core 35 at intervals in the circumferential direction. A rare earth magnet 10 is inserted into each magnet hole 39.

[0015] The motor 30 is preferably used at a maximum rotational speed of 7,500 rpm or higher. The upper limit of the maximum rotational speed is not particularly limited. The maximum rotational speed is, for example, 50,000 rpm or lower. "Used at a maximum rotational speed of 7,500 rpm or higher" refers to a configuration that can be used at a rotational speed of 7,500 rpm or higher under specified conditions, and is not limited to a configuration that is always used at a rotational speed of 7,500 rpm or higher. For example, the motor 30 may be variable speed controlled using an inverter. When variable speed control is used using an inverter, there is a concern that eddy current loss may increase as the inverter's PWM (Pulse Width Modulation) carrier frequency increases. By using rare earth magnet 10, the motor 30 of the present disclosure is expected to reduce eddy current loss even at high rotational speeds of 7,500 rpm or higher.

[0016] In the case of a permanent magnet synchronous motor, the motor of the present disclosure is not limited to an interior permanent magnet (IPM) motor, but may be a surface permanent magnet (SPM) motor. In addition to the permanent magnet synchronous motor, the motor may be a permanent magnet direct current motor, a linear synchronous motor, a voice coil motor, a vibration motor, or the like.

[0017] As illustrated in FIGS. 1 to 3, the rare earth magnet 10 comprises a plurality of magnets 11 and insulating layers 13 present between the plurality of magnets 11.

[0018] (1) Magnet 11 (1.1) Composition of Magnet 11 The magnet 11 is a permanent magnet containing a rare earth element. From the viewpoint of having good magnetic properties, the magnet 11 is preferably a rare earth sintered magnet.

[0019] The composition of magnet 11 is not particularly limited as long as it contains rare earth elements. From the viewpoint of increasing magnetic flux density, the total amount of rare earth elements in magnet 11 is preferably 31.0 mass% or less, and preferably 29.5 mass% or less. The lower limit of the total amount of rare earth elements in magnet 11 may be, for example, 27 mass% or more, 28 mass% or more, or 28.5 mass% or more. The total amount of rare earth elements in magnet 11 can be measured by X-ray fluorescence analysis. The total amount of rare earth elements can be adjusted by changing the content of rare earth elements in the raw materials of magnet 11 and insulating layer 13.

[0020] The magnet 11 may be, for example, a magnet containing a rare earth element (R), a transition metal element (T), and boron (B). Such a magnet is also called an RTB magnet.

[0021] Examples of rare earth elements include one or more selected from the group consisting of neodymium (Nd), praseodymium (Pr), terbium (Tb), dysprosium (Dy), samarium (Sm), yttrium (Y), scandium (Sc), lanthanum (La), cerium (Ce), europium (Eu), gadolinium (Gd), holmium (Ho), ytterbium (Yb), and lutetium (Lu). Among these, the rare earth element preferably includes one or more of Nd, Pr, Dy, and Tb, and more preferably includes Nd as the primary component. Note that "primarily Nd" means that the Nd content (mass%) is the highest among the rare earth elements. The B content is preferably 0.1% to 3% by mass of the entire magnet 11, and more preferably 0.5% to 1.5% by mass.

[0022] Examples of transition metal elements include one or more selected from the group consisting of iron (Fe), cobalt (Co), and nickel (Ni). Among these, from the viewpoint of magnetic properties, it is preferable to include one or more of Fe and Co as the transition metal element, and it is more preferable to include Fe as the main component. Incidentally, "Fe as the main component" means that the content (mass %) of Fe is the highest among the transition metal elements. The content of the transition metal element is preferably 60 mass % or more of the entire magnet 11, more preferably 65 mass % or more. The upper limit of the transition metal element is not particularly limited, and can be, for example, 73 mass % or less of the entire magnet 11. Furthermore, when Fe and Co are included, a portion of the Fe may be substituted with Co. For example, when the total of Fe and Co is 100 mass %, the content of Co can be greater than 0 mass % and less than 1 mass %.

[0023] Magnet 11 may contain elements other than those listed above (hereinafter also referred to as "other elements"). Examples of other elements include one or more selected from the group consisting of aluminum (Al), copper (Cu), zinc (Zn), indium (In), silicon (Si), phosphorus (P), sulfur (S), titanium (Ti), vanadium (V), chromium (Cr), manganese (Mn), nickel (Ni), gallium (Ga), germanium (Ge), zirconium (Zr), niobium (Nb), molybdenum (Mo), palladium (Pd), silver (Ag), cadmium (Cd), tin (Sn), antimony (Sb), hafnium (Hf), tantalum (Ta), and tungsten (W). The content of other elements is preferably 0% to 3% by mass of the entire magnet 11.

[0024] From the viewpoint of improving coercivity, it is more preferable that magnet 11 have a region in which the concentration of heavy rare earth elements decreases from at least a portion of the surface of magnet 11 toward the interior of magnet 11. In FIG. 6, the decrease in concentration of heavy rare earth elements is represented by the shade of the shading. Areas with high concentrations of heavy rare earth elements are shown with dark shading, while areas with low concentrations are shown with light shading. A configuration having a region in which the concentration of heavy rare earth elements decreases can contribute to reducing the amount of heavy rare earth elements added while maintaining magnetic properties. The heavy rare earth elements can be one or more selected from the group consisting of terbium (Tb), dysprosium (Dy), gadolinium (Gd), holmium (Ho), europium (Eu), thulium (Tm), ytterbium (Yb), and lutetium (Lu). Of these, the heavy rare earth elements are preferably one or more of Dy and Tb. The region in magnet 11 where the concentration of the heavy rare earth element is reduced can be formed, for example, by applying a material containing the heavy rare earth element to the surface of magnet 11 and then heat treating it. Details will be explained later.

[0025] The magnet 11 is, for example, Nd ２ Fe １４ Preferably, the magnet 11 has a main phase of B and a rare earth-rich phase that has a higher rare earth element content than the main phase. The magnet 11 may also have a boron-rich phase that has a higher boron content than the main phase. The main phase usually has a tetragonal crystal structure. For example, the above-mentioned Nd ２ Fe １４ B has a tetragonal crystal structure. The main phase of the magnet 11 can be identified by X-ray diffraction (XRD) analysis of the magnet 11 as the component with the largest peak intensity. ２ Fe １４ When the peak intensity of B is the largest, the magnet 11 is Nd ２ Fe １４ It can be determined that the main phase is B.

[0026] (1.2) Average Orientation of Magnets 11 The average orientation of magnets 11 is preferably 90% or more, and more preferably 95% or more. The higher the average orientation of magnets 11, the better, but it is usually 99.5% or less. In Figures 2 and 3, the white arrows indicate the orientation direction. Multiple magnets 11 can be used, for example, lined up in a direction perpendicular to the orientation direction, as shown in Figure 3.

[0027] The average orientation of magnet 11 can be determined, for example, as follows. If magnet 11 is rectangular (quadrature) as shown in Figures 1 and 4, it is cut out to a size compatible with the measuring device and measured. For example, on the rectangular base of magnet 11 in Figure 4, the average orientation is determined as the average orientation of each 1 mm wide section centered on the normal Nn at multiple points Pn from one end of the long side to the other. The number of multiple points Pn is not particularly limited. Figure 4 shows five points P1-P5 and normals N1-N5 at each of points P1-P5. If the size of magnet 11 is sufficiently small, the number of multiple points Pn may be two, but five or more is preferable. The number of multiple points Pn is usually 10 or less. For example, a pulsed high magnetic field measuring device (magnetic field: 4 T) can be used as the measuring device. If the cut-out portion does not fit into the measuring device, a sample of a size that can fit into the measuring device is cut out from the center of the cut-out portion.

[0028] When the magnet 11 has a convex curved shape, as shown in Figures 7 and 8, the average orientation is calculated as the average degree of orientation of each 1 mm wide portion centered on the normal Nn at multiple points Pn from one end to the other on the curve C1 on the convex side of the outer periphery of the magnet 11 as viewed from the first direction (Z-axis direction). The number of points Pn is not particularly limited. When the size of the magnet 11 is sufficiently small, the number of points Pn may be two, but five or more is preferable. The number of points Pn is usually 10 or less. Note that when the magnet 11 has a convex curved shape, the radius of curvature of the curve C1 is not limited to a constant value and may vary.

[0029] Below, a method for calculating the average degree of orientation when the magnet 11 has a convex curved shape will be described in detail with reference to Figures 8 and 9. The curve on the convex side of the periphery of the magnet 11 as viewed from the Z-axis direction is designated as curve C1, and the line tracing the edge opposite curve C1 is designated as opposing line C2. First, as shown in Figure 8, multiple points Pn are identified. In this embodiment, five points P1-P5 are identified. On the magnet 11, points P1 and P5 at both ends of the convex curve C1 are located within 5 mm of one end (e.g., the left end) and within 5 mm of the other end (e.g., the right end). Multiple points (points P2-P4 in this embodiment) are located at equal intervals (four equal positions in this embodiment) between points P1 and P5 at both ends of the curve C1, starting from one end. In this embodiment, point P3 is located in the middle of curve C1.

[0030] On the curve C1, the normal line N1-N5 at each point P1-P5 is identified. A 1 mm wide portion 12 is cut out from the magnet 11, centered on the normal line Nn. Each portion 12 is, for example, approximately rectangular prism-shaped, as shown in FIG. 9. In reality, the top and bottom surfaces of FIG. 9 are curved surfaces. The degree of orientation of each portion 12 is measured, for example, using a pulsed high magnetic field measuring device (magnetic field: 4 T). If the cut-out portion does not fit into the measuring device, a sample of a size that can fit into the measuring device is cut out from the center of the cut-out portion. The average value of the degrees of orientation of each portion 12 is calculated as the average degree of orientation.

[0031] The average degree of orientation of magnet 11 can be controlled, for example, by appropriately designing the magnetic field to be applied in the orientation process described below. For example, even if magnet 11 has a convex curved shape, the above-mentioned average degree of orientation of 90% or more can be achieved by applying a magnetic field that extends in the normal direction of curve C1 of magnet 11 in the orientation process described below.

[0032] (1.3) Shape of Magnet 11 The shape of the magnet 11 is not particularly limited. For example, it is preferable that the magnet 11 be plate-shaped. Plate-shaped magnets 11 have a shorter distance from the surface to the deepest part compared to thicker block-shaped magnets. Therefore, plate-shaped magnets 11 are suitable because they facilitate the diffusion of heavy rare earth elements into the interior when grain boundary diffusion occurs. Plate-shaped magnets 11 can be suitably used as a laminated magnet in which multiple magnets 11 and insulating layers 13 are stacked. The rare earth magnet 10 in FIG. 1 is stacked with multiple magnets 11 stacked in the thickness direction of the plate-shaped magnets 11. In this laminated magnet, the magnets 11 and insulating layers 13 are stacked alternately. In a laminated magnet, each magnet 11 is sometimes referred to as a magnet body. The magnets 11 in FIGS. 1 and 2 are rectangular when viewed from above (Z-axis direction). The magnet 11 may have a shape other than rectangular when viewed from above, and may have a curved shape (such as a circular arc) that is convex in one direction when viewed from above (the positive direction in the X-axis direction in FIG. 8, or the upward direction in FIG. 8), as shown in Figures 7 and 8.

[0033] (1.4) Thickness of Magnet 11 The thickness of magnet 11 is preferably 0.5 mm or more and 4.0 mm or less, and more preferably 1.2 mm or more and 2.5 mm or less. If the thickness of magnet 11 is 0.5 mm or more, it is easy to form magnet 11 while ensuring an average degree of orientation. If the thickness of magnet 11 is 4.0 mm or less, it is easy to diffuse the heavy rare earth element to the interior. Furthermore, if the thickness is 4.0 mm or less, eddy current loss inside rare earth magnet 10 can be suitably reduced. The dimensions of plate-shaped magnet 11 in the direction perpendicular to the thickness are not particularly limited. For example, magnet 11 can be 0.5 mm or more and 4.0 mm or less in thickness, 4 mm or more and 10 mm or less in length, and 10 mm or more and 30 mm or less in width.

[0034] (2) Insulating Layer 13 (2.1) Composition of Insulating Layer 13 The insulating layer 13 is mainly composed of inorganic crystals. The inorganic crystals are preferably non-magnetic crystalline particles. "Mainly composed of inorganic crystals" means that the content of inorganic crystals in the insulating layer 13 is 50% by mass or more. The content of inorganic crystals in the insulating layer 13 is preferably 80% by mass or more, more preferably 90% by mass or more, and may be 100% by mass. The composition of the insulating layer 13 can be analyzed by the following method. The presence of inorganic crystals is determined by X-ray microanalysis or XRD analysis, and the content of inorganic crystals is calculated in combination with composition analysis by EPMA (Electron Probe Micro Analyser).

[0035] The insulating layer 13 is made of inorganic crystals such as CaF ２ , BaF ２ , SrF ２ , MgF ２ , Al ２ O ３ , ZrO ２ , Dy ２ O ３ , Tb ２ O ３ , Nd ２ O ３ , TbF ３ , DyF ３ , LiF, SiO ２ , BN, ZrB ２ , Si ３ N ４ , TiB ２ , Pr ２ O ３ From the viewpoint of reducing eddy current loss, the insulating layer 13 preferably contains at least a fluoride of Group 2A of the periodic table as an inorganic crystal. The insulating layer 13 preferably contains CaF as the fluoride of Group 2A of the periodic table. ２ , BaF ２ , SrF ２ , and MgF ２ It is more preferable that the insulating layer 13 contains at least one selected from the group consisting of CaF ２ It is particularly preferred that the composition contains:

[0036] When the total mass of the inorganic crystals is taken as 100 mass %, the insulating layer 13 preferably contains 80 mass % or more, more preferably 90 mass % or more, and even more preferably 95 mass % or more of a fluoride of Group 2A of the periodic table as the inorganic crystals. The upper limit of the content of the fluoride of Group 2A of the periodic table is not particularly limited, and may be, for example, 100 mass %.

[0037] When the insulating layer 13 is primarily composed of a Group 2A fluoride, the raw material for the insulating layer 13 preferably contains the above-mentioned heavy rare earth element compound in addition to the Group 2A fluoride. If the raw material for the insulating layer 13 contains the above-mentioned heavy rare earth element compound, the heavy rare earth element can be favorably diffused into the magnet 11. The heavy rare earth element contained in the raw material for the insulating layer 13 diffuses into the magnet 11 after heat treatment. Therefore, the insulating layer 13 of the resulting rare earth magnet 10 contains almost no heavy rare earth element. The mass ratio of the Group 2A fluoride to the heavy rare earth element compound in the raw material for the insulating layer 13 is not particularly limited. The mass ratio of the Group 2A fluoride to the heavy rare earth element compound in the raw material for the insulating layer 13 can be, for example, 20:80-40:60.

[0038] (2.2) Presence and Arrangement of Insulating Layer 13 It is sufficient that insulating layer 13 is present at least between magnets 11, 11. The arrangement of insulating layer 13 is, for example, as follows: Insulating layer 13 may be arranged so as to cover the entire surface of magnet 11 (see FIG. 5). In the example of FIG. 5, both upper and lower main surfaces 11A and both side surfaces 11B of each magnet 11 are covered with insulating layer 13, and insulating layer 13 is arranged so as to cover the entire surface of magnet 11. In the example of FIG. 3, the side surfaces 11B of each magnet 11 are not covered with insulating layer 13, and insulating layer 13 is arranged so as to cover only a portion of the surface of magnet 11. 3, the magnet 11 in the top row has one main surface 11A (lower side) covered with an insulating layer 13, but the other main surface 11A (upper side) is not covered with an insulating layer 13, and the insulating layer 13 is arranged in a manner that covers a portion of the surface of the magnet 11. Similarly, in the example of FIG. 3, the magnet 11 in the bottom row has one main surface 11A (upper side) covered with an insulating layer 13, but the other main surface 11A (lower side) is not covered with an insulating layer 13, and the insulating layer 13 is arranged in a manner that covers a portion of the surface of the magnet 11. Furthermore, the insulating layer 13 may be arranged between the multiple magnets 11 in a manner that extends from one side surface 11B of the magnet 11 (e.g., the left surface in FIGS. 3 and 4) to the other side surface 11B (e.g., the right surface in FIGS. 3 and 5) (see FIGS. 3 and 5), or may be arranged in a manner that partially separates the magnets 11. In other words, as long as the rare earth magnet 10 has portions where the magnets 11 are insulated from each other by the insulating layer 13, the magnets 11 may have portions where they are partially connected to each other.

[0039] The insulating layer 13 is preferably provided so as to be in direct contact with the magnet 11. The insulating layer 13 may also be an insulating bonding layer that bonds (adheses) the magnets 11, 11 located on both sides. From the viewpoint of bonding the magnets 11, 11 with sufficient strength, the insulating layer 13 preferably has a region in the direction in which the multiple magnets 11 are aligned (the Z-axis direction) where components derived from the insulating layer 13 and components derived from the magnet 11 are mixed. Such a rare earth magnet 10 can be suitably formed by hot pressing. The conditions for hot pressing will be explained later.

[0040] The insulating layers 13 may be provided along the orientation direction of the magnetic field of each magnet 11 (e.g., the X-axis direction in FIG. 3 , the direction of the white arrow in FIG. 3 ), or along a direction intersecting the orientation direction (e.g., the X-axis direction in FIG. 3 ) (e.g., the Z-axis direction in FIG. 3 ). Note that, as shown in FIG. 10 , when the rare earth magnet 10 is used as a motor magnet, etc., the insulating layers 13 are preferably provided along the orientation direction of the magnets 11 (the X-axis direction in FIG. 10 ) from the perspective of efficiently reducing eddy current loss. With this configuration, the insulating layers 13 are arranged approximately parallel to the direction in which the magnetic flux generated in the stator 31 passes through the rare earth magnet 10 (the X-axis direction in FIG. 10 ), thereby effectively reducing eddy current loss.

[0041] (2.3) Thickness of Insulating Layer 13 The thickness T of insulating layer 13 is not particularly limited. From the viewpoint of ensuring sufficient insulation, the thickness T of insulating layer 13 is preferably 5 μm or more, more preferably 9 μm or more, and even more preferably 12 μm or more. From the viewpoint of ensuring magnetic properties, the thickness T of insulating layer 13 is preferably 30 μm or less, more preferably 25 μm or less, and even more preferably 18 μm or less. From these viewpoints, the thickness T of insulating layer 13 is preferably 5 μm or more and 30 μm or less, more preferably 9 μm or more and 25 μm or less, and even more preferably 12 μm or more and 18 μm or less. The thickness T of insulating layer 13 is measured, for example, by observing the cross section of rare earth magnet 10 with a scanning electron microscope (SEM) and measuring the distance between magnets 11 located on both sides of insulating layer 13 (see Figure 6).

[0042] 2. Manufacturing Method of Rare Earth Magnet 10 There are no particular limitations on the manufacturing method of rare earth magnet 10. An example of a manufacturing method for rare earth magnet 10, which is a laminated magnet in which magnets 11 and insulating layers 13 are alternately stacked, is shown below.

[0043] (1) SC Alloy Preparation Step A raw alloy (strip cast alloy (SC alloy)) containing rare earth elements, transition metal elements, boron, and the like is prepared.

[0044] (2) Hydrogen decomposition process: In a hydrogen atmosphere, the SC alloy is allowed to absorb hydrogen at a predetermined temperature (e.g., 200°C) for a predetermined time (e.g., 1 to 5 hours), thereby embrittling the grain boundaries (rare earth-rich phase) of the SC alloy.

[0045] (3) Coarse Crushing Step, First Lubricant Addition Step The SC alloy powder that has undergone the hydrogen cracking step is coarsely crushed (coarse crushing step). At this time, a lubricant may be added to the SC alloy powder (first lubricant addition step). This step may be performed, for example, in an inert atmosphere (nitrogen atmosphere, argon atmosphere, etc.).

[0046] (4) Fine Pulverization Step, Second Lubricant Addition Step The SC alloy powder obtained after the coarse pulverization step is pulverized to a predetermined average particle size D50 (fine pulverization step). The average particle size D50 can be, for example, 2.0 μm-3.5 μm. At this time, a lubricant may be added to the finely pulverized SC alloy powder to improve the flowability of the pulverized powder (second lubricant addition step). This step is preferably performed in an inert atmosphere (such as a nitrogen atmosphere or an argon atmosphere).

[0047] (5) Powder Filling Process, Orientation Process, and Molding Process The SC alloy powder after the pulverization process is filled into a mold. This process is preferably performed, for example, under an inert atmosphere (such as a nitrogen atmosphere or an argon atmosphere). The mold has multiple molding spaces of a predetermined thickness. Each molding space is separated, for example, by multiple partition plates. A magnetic field is applied in a predetermined direction to the mold after powder filling to align the orientation of the SC alloy powder. The SC alloy powder filled into the mold is then compressed to form an SC alloy compact. In this way, an SC alloy compact having a predetermined degree of orientation (e.g., an average orientation of 90% or more) and a predetermined thickness (e.g., a thickness of 1.2 mm to 2.5 mm) can be obtained without a cutting process.

[0048] (6) Mold Breaking Step, First Firing Step The molded body is removed from the mold (mold breaking step). The molded body is sintered at a predetermined sintering temperature (e.g., 900°C-1200°C) for a predetermined time (e.g., 2 hours-5 hours) (first sintering step). This sintering is preferably carried out in a vacuum. Prior to this sintering, heating at a temperature lower than the sintering temperature may be carried out for dehydrogenation.

[0049] (7) Insulating Layer Coating Step The raw material for the insulating layer 13 is coated on the surface of the fired compact. The raw material for the insulating layer 13 can be, for example, a mixture of raw material powder of inorganic crystalline components, compound powder containing a heavy rare earth element, and a solvent. The raw material for the insulating layer 13 may be coated on at least one main surface of the compact, or may be coated on both main surfaces. The main surface of the compact is the surface corresponding to the main surface 11A of the magnet 11. The raw material for the insulating layer 13 may be coated on the entire surface of the compact, i.e., on both main surfaces and side surfaces if the compact is plate-shaped.

[0050] (8) Laminate Temporarily Fixing Process: A predetermined number of molded bodies coated with an insulating layer are stacked and temporarily fixed. Hereinafter, the temporarily fixed stack of molded bodies will also be referred to as a laminate. This method makes it possible to manufacture plate-shaped magnets 11 without the need for a cutting process or other process to cut out plate-shaped magnets from a larger magnet.

[0051] (9) Hot Pressing Step The temporarily fixed laminate is placed in a hot press mold and subjected to uniaxial hot pressing. This step is carried out, for example, under a vacuum atmosphere (for example, 10 －３ Pa-10 －４The hot pressing may be performed under a pressure of 1000 psi (1000 Pa) or in an inert atmosphere (such as a nitrogen atmosphere or an argon atmosphere). The hot pressing temperature may be, for example, 700°C-1100°C. The hot pressing time may be, for example, 1 second to 1 hour. The hot pressing pressure is preferably 3 MPa or more, more preferably 5 MPa or more, and even more preferably 8 MPa or more. There is no particular upper limit to the hot pressing pressure, and it may be, for example, 100 MPa or less. The hot pressing heat treatment time may be, for example, 10 minutes to 20 hours. Through the above series of steps, a rare earth magnet 10 comprising magnets 11 and insulating layers 13 is produced. The rare earth magnet 10 is formed by bonding multiple magnets 11 together with insulating layers 13, forming an integrated magnet.

[0052] The hot pressing process allows the heavy rare earth elements (Tb, Dy, etc.) contained in the raw material of the applied insulating layer 13 to diffuse into the magnet 11. The hot pressing process also allows the magnet 11 (e.g., Nd ２ Fe １４ B) flows out to the surface of the magnet 11, and the rare earth element (Nd element) in the magnet 11 flows out to the surface of the magnet 11. ２ A surface layer of a rare earth-rich phase (Nd-rich phase) can be formed near the interface with the insulating layer 13. Furthermore, this hot pressing process can make the insulating layer 13 sufficiently thin and uniform in thickness.

[0053] The rare earth magnet 10 obtained as described above can be considered to be a rare earth magnet manufactured by hot pressing (hot uniaxial pressing) a laminate consisting of at least a pair of magnets 11, 11 (sintered SC alloys) sandwiching the raw material for the insulating layer 13, so that pressure is applied in a direction that crushes the raw material for the insulating layer 13. Alternatively, the rare earth magnet 10 can be considered to be a rare earth magnet manufactured by arranging a first magnet 11 (sintered SC alloy), the raw material for the insulating layer 13, and a second magnet 11 (sintered SC alloy) in this order to form a laminate, and then applying pressure to the first magnet 11 and the second magnet 11 from both sides while heating the laminate. The raw material for the insulating layer 13 preferably contains inorganic crystals. The raw material for the insulating layer 13 may also contain a component containing a heavy rare earth element. For example, the raw material for the insulating layer 13 may be CaF ２ and TbF ３ When the total of CaF is taken as 100 mass % ２ It is preferable that the content of TbF is 20 mass % to 40 mass %. ３ It is preferable that the content is 60 mass % to 80 mass %.

[0054] 3. Functions and Effects of the Present Embodiment Because the motor 30 of this embodiment includes a rare earth magnet 10, it is possible to suppress efficiency declines due to eddy current loss. The reason for this is presumed to be as follows. However, the present disclosure is not limited to this presumption. Because the insulating layer 13 of the rare earth magnet 10 of this embodiment is primarily composed of inorganic crystals, eddy current loss is unlikely to change in high-temperature environments. Since the insulating layer 13, which is primarily composed of inorganic crystals, shows almost no change in resistance from room temperature (e.g., 25°C) to 150°C, it is presumed that eddy current loss reduction can be achieved over a wide temperature range. Furthermore, because the insulating layer 13, which is primarily composed of inorganic crystals, has a thermal expansion coefficient close to that of the magnet 11, it is believed that the insulating layer 13 is unlikely to deteriorate even with thermal cycling. Note that the difference in thermal expansion coefficient between the insulating layer 13 and the magnet 11 is ±3.0 × 10 －５ / K or less. It is presumed that this is also the reason why the durability (heat resistance) of the rare earth magnet 10 of this embodiment is improved.

[0055] When used at a maximum rotational speed of 7,500 rpm or more, the effect of suppressing efficiency decline due to eddy current loss is particularly effective. In motors equipped with conventional magnets, in the high frequency range of operating frequencies above 5 kHz, eddy current loss generated inside the magnet can cause the magnet to heat up, resulting in a significant decline in motor efficiency. On the other hand, in motor 30 equipped with rare earth magnet 10, eddy current loss generated inside rare earth magnet 10 can be reduced, even in the high frequency range of operating frequencies above 5 kHz, making it less likely to result in a significant decline in motor efficiency. [Example]

[0056] The present disclosure will be explained in more detail below with reference to examples.

[0057] 1. Fabrication of Laminated Magnets as Rare Earth Magnets In Experimental Examples 1A to 5A, 1B, and 2B, "laminated magnets" corresponding to "rare earth magnet 10" were fabricated.

[0058] <Experimental Examples 1A to 5A> (1) SC Alloy Preparation Step The main raw materials of a Nd / Pr alloy, an alloy containing Co, Al, Cu, Ga, and Zr, and a metal element were mixed to prepare a strip cast alloy (SC alloy) (for example, composition: Nd ２ Fe １４ B) was prepared under an argon atmosphere. The SC alloy was a plate-shaped powder with a main surface dimension of 10 mm × 10 mm to 20 mm × 20 mm.

[0059] (2) Hydrogen Crushing Step The SC alloy was allowed to absorb hydrogen in a hydrogen furnace (hydrogen atmosphere, 200°C, 2 hours) to embrittle the grain boundaries (neodymium-rich phases) of the SC alloy.

[0060] (3) Coarse grinding step, first lubricant addition step A lubricant was added to the SC alloy powder that had undergone the hydrogen crushing step. Methyl caprylate was used as the lubricant. The lubricant was mixed at a ratio of 0.03% by mass to 0.07% by mass relative to the amount of SC alloy. While adding the lubricant to the SC alloy powder, the powder was coarsely ground using a stirrer in a nitrogen or argon atmosphere. The average particle size of the SC alloy after coarse grinding was 50 μm to 500 μm.

[0061] (4) Fine pulverization step, second lubricant addition step The SC alloy powder after adding the lubricant was finely pulverized in a nitrogen atmosphere using a jet mill. The average particle size D50 after fine pulverization was 2.0 μm-3.5 μm. A lubricant was added to the SC alloy powder after fine pulverization. Methyl laurate was used as the lubricant. The mixing ratio of the lubricant to the amount of SC alloy was 0.05% by mass-0.1% by mass.

[0062] (5) Powder Filling Step, Orientation Step, and Compacting Step The SC alloy powder after the pulverization step and the second lubricant addition step was filled into each molding space of a mold provided with multiple partition plates in a nitrogen atmosphere. Each compact formed in each molding space corresponds to each magnet to be stacked in a subsequent step. In the samples of Experimental Examples 1A to 5A and Experimental Examples 1B and 2B, each magnet was a rectangular parallelepiped with dimensions of 2 mm thick x 5 mm x 16 mm. A magnetic field (e.g., 5000 V) was applied to the mold after powder filling in the planar direction of each compact (direction perpendicular to the thickness direction) to align the orientation of the SC alloy powder. The SC alloy powder filled in the mold was compressed to form an SC alloy compact. The pressure molding conditions were pressure: 5 MPa-20 MPa, packing density: 3.0 g / cm. ３ -4.0 g / cm ３ , relative density: 40%-52%.

[0063] (6) Mold Disassembly Process, First Firing Process The outer frame was removed from the mold, and a continuous arrangement of molded bodies and partition plates (the object to be fired) was prepared. For dehydrogenation, the object to be fired (with the partition plates) was heated at 500°C for 3-4 hours in an Ar atmosphere. Thereafter, the object to be fired (with the partition plates) was held at 930°C-1050°C for 3 hours and fired in a vacuum atmosphere.

[0064] (7) Insulating Layer Coating Step After the first firing step, the partition plates were removed from the sintered object, and the raw material for the insulating layer was coated on six surfaces of the magnet before lamination. The raw material for the insulating layer consisted of the compound powder of the main component listed in Table 1 and TbF ３ The compound powder and the solvent were mixed. ３The ratio of the compound powder was 10 mass % to 20 mass %. The thickness of the insulating layer raw material was 12 μm or more and 14 μm or less. The insulating layer raw material was applied in the air by a spray method.

[0065] (8) Laminate Temporarily Fixing Process 25 magnets coated with an insulating layer were stacked in air and temporarily fixed. The number of magnets stacked was adjusted so that the dimension of the laminated magnet in the stacking direction was 50 mm. This method allows for the production of plate-shaped magnets without the need for a cutting process or other process to cut out plate-shaped magnets from a larger magnet.

[0066] (9) Hot Pressing Step The temporarily fixed laminate was placed in a hot press mold and subjected to uniaxial hot pressing. This step was carried out under a vacuum atmosphere (for example, 10 －３ Pa-10 －４ The hot pressing was carried out in a vacuum atmosphere (700-1100°C), or in an inert atmosphere (nitrogen atmosphere, argon atmosphere). The hot pressing temperature was 700-1100°C, the hot pressing time was 1 second to 1 hour, the hot pressing pressure was 3 MPa or more and 100 MPa or less, and the hot pressing heat treatment time was 10 minutes to 20 hours. In this manner, laminated magnet samples for Experimental Examples 1A to 5A were produced.

[0067] <Experimental Example 1B> In Experimental Example 1B, the insulating layer coating step and pressing step described below were performed instead of the insulating layer coating step (7) and hot pressing step (9). The steps other than the insulating layer coating step and pressing step described below were the same as the steps (1) to (6) and (8) described above for Experimental Examples 1A to 5A, and a laminated magnet sample for Experimental Example 1B was produced.

[0068] In Experimental Example 1B, in the insulating layer coating step, first, TbF ３ A mixture of the compound powder and solvent was applied to the substrate. The substrate was then heat-treated until the coating film on the surface was completely removed. After that, a resin having the main component shown in Table 1 was applied.

[0069] In Experimental Example 1B, the temporarily fixed laminate was placed in a press mold and pressed uniaxially under atmospheric pressure at a temperature of 25°C for a time longer than the time required for the resin to harden, and at a pressure of 3 MPa.

[0070] <Experimental Example 2B> Experimental Example 2B was not a laminated magnet, but a single magnet with a thickness of 50 mm. The planar shape of the magnet was a rectangle measuring 5 mm x 16 mm, similar to Experimental Examples 1A to 5A. Except for the magnet thickness of 50 mm, the same (1) SC alloy preparation step, (2) hydrogen decomposition step, (3) coarse pulverization step, first lubricant addition step, (4) fine pulverization step, second lubricant addition step, (5) powder filling step, orientation step, and molding step were performed as in Experimental Examples 1A to 5A. The resulting compact was a block without a partition plate interposed between them. For the mold-breaking step and first firing step of Experimental Example 2B, the outer frame was removed from the mold to prepare a compact (object to be fired). Then, heating for dehydrogenation and firing were performed under the same conditions as in the above-mentioned (6) mold-breaking step and first firing step. After the first firing step, the raw material for the insulating layer was applied to six surfaces of the magnet of Experimental Example 2B. The raw material for the insulating layer and the thickness of the applied raw material for the insulating layer were the same as those of Experimental Examples 1A to 5A. The magnet with the raw material for the insulating layer applied was placed in a hot press mold and subjected to uniaxial hot pressing as in Experimental Examples 1A to 5A.

[0071] 2. Characteristics of Experimental Examples 1A to 5A, 1B, and 2B Table 1 summarizes the characteristics of the magnets and insulating layers of Experimental Examples 1A to 5A, 1B, and 2B. The "Type" column of "Magnet" indicates the type of magnet. "Neodymium magnet" refers to Nd ２ Fe １４ This indicates that the magnet has B as its main phase. The "Insulating Layer" column indicates the compound that is contained in the insulating layer in the largest amount (mass %). With regard to the components of the insulating layer, inorganic substances were identified using EPMA and XRD, and organic substances were identified using NMR and IR analysis. The "Number of Divisions" column indicates the number of divisions of the laminated magnet, i.e., the number of layers of the magnet. Since Experimental Example 2B is an undivided rare earth magnet, the number of divisions was set to "0".

[0072]

[0073] 3. Performance Evaluation (1) Evaluation Method of Magnet Temperature The magnets of Experimental Examples 1A to 5A, 1B, and 2B were each attached to a motor, and a test was conducted in which the motor was driven for 0.5 hours at a maximum torque of 500 N m and a maximum rotational speed of 10,000 rpm. Immediately after the test, the surfaces of the magnets of Experimental Examples 1A to 5A, 1B, and 2B were observed with a laser, and the surface temperature (°C) was measured.

[0074] (2) Method for Evaluating Magnet Temperature After 200 Hours of Operation Each motor subjected to "(1) Method for Evaluating Magnet Temperature" was further tested by operating it for 200 hours at a maximum torque of 500 N m and a maximum rotational speed of 10,000 rpm. Immediately after the test, the surface of the magnet of each of Experimental Examples 1A to 5A, 1B, and 2B was observed with a laser to measure the surface temperature (°C). The surface temperature after 0.5 hours of operation was set as 100%, and the rate of change (%) of the surface temperature of the laminated magnet of Experimental Example 1A to 5A and 1B was calculated. A small rate of change (%) is an indicator that temperature rise is suppressed and thermal degradation is less likely to occur. Rate of change (%) = (T ２００ -T ０．５ ) / T ０．５ x100 T ０．５ T: Surface temperature after 0.5 hours of operation (°C) ２００ : Surface temperature after 200 hours of operation (°C)

[0075] The evaluation was made as follows: Magnet temperature (change after 200 hours) "A": rate of change 10% or less "B": rate of change greater than 10%

[0076] (3) Method of Evaluating Efficiency Region For the motors equipped with the magnets of Experimental Examples 1A to 5A, 1B, and 2B, a graph of rotation speed-torque characteristics was obtained, with the horizontal axis representing rotation speed (rpm) and the vertical axis representing torque (N m). Motor efficiency is expressed as the ratio of the output (W) from the motor to the input power (W) input to the motor. Motor efficiency (%) can be calculated using the following formulas: Motor efficiency (%) = (output (W) / input power (W)) x 100 Output (W) = 2π x rotation speed (s －１ ) x torque (N m) 1 (rpm) = 1 / 60 (s －１ )

[0077] In the graph of the rotation speed-torque characteristics of the motors described above, the area of ​​the high efficiency region where the motor efficiency was 90% or higher was calculated. The area A2 of the high efficiency region of the motor of Experimental Example 2B was set to 100%, and the rate of change (%) of the area As of the high efficiency region of the motors of Experimental Examples 1A to 5A and 1B was calculated. A large rate of change (%) indicates that the area of ​​the high efficiency region is large and that a decrease in motor efficiency is suppressed. Rate of change (%) = (As - A2) / A2 x 100 A2: Area of ​​the high efficiency region of the motor of Experimental Example 2B As: Area of ​​the high efficiency region of the motors of Experimental Examples 1A to 5A and 1B

[0078] The evaluation was made as follows: Efficiency range "A": rate of change 5% or more "B": rate of change less than 5%

[0079] 4. Evaluation Results The evaluation results are also shown in Table 1. Experimental Examples 1A to 5A satisfy the following requirements (a) and (b). In contrast, Experimental Example 1B does not satisfy the following requirement (b). Experimental Example 1B does not satisfy the following requirements (a) and (b). Requirement (a): The rare earth magnet has multiple magnets and insulating layers present between the multiple magnets. Requirement (b): The insulating layer is primarily composed of inorganic crystals.

[0080] Experimental Examples 1A to 5A were rated "A" for magnet temperature after 200 hours of operation. Experimental Examples 1A to 5A were rated "A" for efficiency range. In contrast, Experimental Example 1B was rated "B" for magnet temperature after 200 hours of operation, and was rated "B" for efficiency range. It was suggested that Experimental Examples 1A to 5A can reduce eddy current loss generated inside the magnet in a high-temperature environment, and can suppress efficiency decline. Such motors are considered to be useful in high-speed rotation motors used in high rotation speed ranges (for example, rotation speeds of 7,500 rpm or more).

[0081] 5. Effects of the Examples Experimental Examples 1A to 5A were able to suppress the decrease in efficiency.

[0082] The present invention is not limited to the above-described embodiments, and various modifications and variations are possible within the scope of the claims of the present invention.

[0083] <<Second Embodiment>> A second embodiment of the present disclosure will be described in detail below. In the second embodiment, when a numerical range is indicated using "-", it is assumed that the range includes both the lower and upper limits unless otherwise specified. For example, the expression "10-20" includes both the lower limit "10" and the upper limit "20". In other words, "10-20" has the same meaning as "10 or more and 20 or less". Furthermore, in this specification, the upper and lower limits of each numerical range can be arbitrarily combined. Hereinafter, the Z-axis direction in each figure is the stacking direction (first direction) of the magnet laminate 110. One direction perpendicular to the Z-axis direction is the X-axis direction (also referred to as the second direction), and the direction perpendicular to the Z-axis direction and the X-axis direction is the Y-axis direction.

[0084] 1. Motor 130 The motor 130 includes a magnet stack 110. The magnet stack 110 is formed by stacking a plurality of magnets 111 and an insulating layer 113 in a first direction. The magnet 111 contains a rare earth element. When viewed from the first direction, the magnet 111 has a curved shape that is convex in a second direction, and the average orientation of each 1 mm wide portion centered on the normal line at multiple points on the curve on the convex side in the second direction from one end to the other of the outer periphery of the magnet 111 when viewed from the first direction is 90% or more. The insulating layer 113 is primarily composed of inorganic crystals.

[0085] The magnet laminate 110 of the present disclosure has low eddy current loss generated inside and is capable of concentrating magnetic flux, and therefore can contribute to one or more of the following effects: miniaturization of the motor, suppression of heat generation, improved heat resistance, and improved heat dissipation.

[0086] The motor 130 of the present disclosure is preferably a rotary motor. An example of a motor 130 including a magnet stack 110 will be described below with reference to FIGS. 19 and 20 . The motor 130 includes a stator 131 and a rotor 133 arranged inside the stator 131. The magnet stack 110 is arranged in the rotor 133, and a winding (not shown) is arranged in the stator 131. The motor 130 of FIG. 19 is an inner rotor type in which the magnets are arranged on the inside (rotating shaft side) and the windings are arranged on the outside. The motor is not limited to the inner rotor type. For example, the motor may be an outer rotor type in which the windings are arranged on the inside (rotating shaft side) and the magnets are arranged on the outside.

[0087] The rotor 133 includes a rotating shaft 134, a rotating core 135, and a plurality of laminated magnets 110. The rotating core 135 is formed by laminating electromagnetic steel sheets. A shaft hole 137 is formed in the center of the rotating core 135. The rotating shaft 134 is inserted into the shaft hole 137. A plurality of magnet holes 139 are formed in the rotating core 135 at intervals in the circumferential direction. A laminated magnet 110 is inserted into each magnet hole 139. Each laminated magnet 110 is arranged with the convex side of its convex curved shape facing the rotating shaft 134. Note that the arrangement of the laminated magnets 110 is not limited to the arrangement shown in FIG. 20. For example, two magnets may be arranged side by side in an arc, as in the rotor of sample C shown in the lower part of FIG. 23.

[0088] The motor 130 is preferably used at a maximum rotational speed of 7,500 rpm or higher. The upper limit of the maximum rotational speed is not particularly limited. The maximum rotational speed is, for example, 50,000 rpm or lower. "Used at a maximum rotational speed of 7,500 rpm or higher" refers to a configuration that can be used at a rotational speed of 7,500 rpm or higher under specified conditions, and is not limited to a configuration that is always used at a rotational speed of 7,500 rpm or higher. For example, the motor 130 may be variable speed controlled using an inverter. When variable speed control is used using an inverter, there is a concern that eddy current loss may increase as the inverter's PWM (Pulse Width Modulation) carrier frequency increases. By using the laminated magnet 110, the motor 130 of the present disclosure is expected to reduce eddy current loss even at high rotational speeds of 7,500 rpm or higher.

[0089] In the case of a permanent magnet synchronous motor, the motor of the present disclosure is not limited to an interior permanent magnet (IPM) motor, but may be a surface permanent magnet (SPM) motor. In addition to the permanent magnet synchronous motor, the motor may be a permanent magnet direct current motor, a voice coil motor, a vibration motor, or the like.

[0090] As illustrated in FIGS. 12 to 14, the magnet stack 110 has a plurality of magnets 111 and insulating layers 113 stacked in a first direction.

[0091] (1) Magnet 111 The composition of the magnet 111 is the same as that explained in the section "(1.1) Composition of the magnet 11" in the first embodiment, and the description in this section applies as is.

[0092] The average degree of orientation of the magnets 111 and a method for measuring it will be described later. In Figures 13 and 14, the outline arrows indicate the orientation direction. Multiple magnets 111 can be used, for example, lined up in a direction perpendicular to the orientation direction, as shown in Figure 14.

[0093] The shape of the magnet 111 is not particularly limited. The magnet 111 is preferably, for example, plate-shaped. The plate-shaped magnet 111 has a shorter distance from the surface to the deepest part compared to a thicker block-shaped magnet. Therefore, the plate-shaped magnet 111 is suitable because it facilitates the diffusion of heavy rare earth elements into the interior when the heavy rare earth elements are diffused through grain boundaries. Plate-shaped magnets 111 can be suitably used as a laminated magnet in which multiple magnets 111 and insulating layers 113 are stacked. The laminated magnet 110 of FIG. 12 includes multiple magnets 111 stacked with the thickness direction of the plate-shaped magnet 111 as the stacking direction. In this laminated magnet 110, the magnets 111 and insulating layers 113 are alternately stacked. In a laminated magnet, each magnet 111 is sometimes referred to as a magnet body. The shape of the magnet 111 viewed from the first direction (Z-axis direction) will be described later.

[0094] The thickness of the magnet 111 is the same as that explained in the section "(1.4) Thickness of the magnet 11" in the first embodiment, and the description in this section applies as is.

[0095] (2) Insulating Layer 113 The composition of the insulating layer 113 is the same as that explained in the section "(2.1) Composition of Insulating Layer 113" in the first embodiment, and the description in this section applies as is.

[0096] The insulating layer 113 only needs to be present between the magnets 111, 111. The insulating layer 113 may be arranged, for example, as follows: The insulating layer 113 may be arranged so as to cover the entire surface of the magnet 111 (see FIG. 15). In the example of FIG. 15, both the upper and lower main surfaces 11A and both side surfaces 11B of each magnet 111 are covered with the insulating layer 113, and the insulating layer 113 is arranged so as to cover the entire surface of the magnet 111. The insulating layer 113 may be arranged so as to cover only a portion of the surface of the magnet 111 (see FIG. 14). In the example of FIG. 14, the side surfaces 11B of each magnet 111 are not covered with the insulating layer 113, and the insulating layer 113 is arranged so as to cover only a portion of the surface of the magnet 111. 14, the topmost magnet 111 has one (lower) main surface 11A covered with insulating layer 113, but the other (upper) main surface 11A is not covered with insulating layer 113, with insulating layer 113 arranged to cover part of the surface of magnet 111. Similarly, in the example of Fig. 14, the bottommost magnet 111 has one (upper) main surface 11A covered with insulating layer 113, but the other (lower) main surface 11A is not covered with insulating layer 113, with insulating layer 113 arranged to cover part of the surface of magnet 111.

[0097] The insulating layer 113 is preferably provided so as to be in direct contact with the magnet 111. The insulating layer 113 may also be an insulating bonding layer that bonds (adheses) the magnets 111, 111 located on both sides. From the viewpoint of bonding the magnets 111, 111 with sufficient strength, the insulating layer 113 preferably has a region in the direction in which the multiple magnets 111 are arranged (the Z-axis direction) where components derived from the insulating layer 113 and components derived from the magnet 111 are mixed. Such a magnet stack 110 can be suitably formed by hot pressing. The conditions for hot pressing will be described later.

[0098] The insulating layers 113 may be provided along the orientation direction of the magnetic field of each magnet 111 (e.g., the X-axis direction in FIG. 14 , the direction of the white arrow in FIG. 14 ), or along a direction intersecting the orientation direction (e.g., the X-axis direction in FIG. 14 ) (e.g., the Z-axis direction in FIG. 14 ). Note that, as shown in FIG. 19 , when the magnet stack 110 is used as a motor magnet or the like, the insulating layers 113 are preferably provided along the orientation direction of the magnets 111 (the X-axis direction in FIG. 19 ) from the perspective of efficiently reducing eddy current loss. With this configuration, the insulating layers 113 are arranged approximately parallel to the direction in which the magnetic flux generated in the stator 131 passes through the magnet stack 110 (the X-axis direction in FIG. 19 ), thereby effectively reducing eddy current loss.

[0099] The thickness of the insulating layer 113 is the same as that explained in the section "(2.3) Thickness of the insulating layer 113" in the first embodiment, and the description in this section applies as is.

[0100] (3) Configuration of the magnet stack 110 From the viewpoint of reducing eddy current loss, it is preferable that 10 or more magnets 111 are used per 50 mm of the dimension of the magnet stack 110 in the first direction, preferably 20 or more magnets, and preferably 25 or more magnets. There is no particular upper limit on the number of magnets, and it may be, for example, 35 or less.

[0101] (4) Shape of magnet 111 as viewed from the first direction When viewed from the first direction, magnet 111 has a curved shape that is convex in the second direction. In this embodiment, the first direction corresponds to the Z-axis direction. The second direction corresponds to the X-axis direction.

[0102] The shape of magnet 111 is not particularly limited as long as it is a curved shape that is convex in the second direction. Magnet 111 is preferably arc-shaped from the viewpoint of concentrating magnetic flux. In this disclosure, an arc-shaped shape is defined as a shape in which, on the periphery of the magnet as viewed from the first direction, a curve C1 on the convex side is generally arc-shaped, and a line opposing curve C1 (an opposing line C2, described below) is also generally arc-shaped. In other words, the arc-shaped shape includes two generally arc-shaped curves that extend parallel to each other on the contour line of the periphery of the magnet as viewed from the first direction. Magnet 111 may also have a convex curved shape other than an arc-shaped shape.

[0103] The magnet 111 in Figures 16 and 17 will be specifically described below, with the curve C1 representing the convex curve on the periphery of the magnet 111 as viewed from the Z-axis direction, and the opposing line C2 representing the line that traces the edge opposite to the curve C1. The magnet 111 in Figure 16 is an arc-shaped magnet. The curve C1 is a perfect circular arc. The radius of curvature of the curve C1 is constant. The opposing line C2 is a perfect circular arc that is concentric with the curve C1. In Figure 16, the center of curvature of the curve C1 and the opposing line C2 is indicated by point O. The opposing line C2 is a curve (a parallel curve to the curve C1) that is a constant distance from each point on the curve C1 in the normal direction. The magnet 111 in Figure 17 is an example of a convex curved shape other than an arc shape. This magnet 111 is approximately U-shaped. The curve C1 is a curve with a variable radius of curvature. Specifically, the curve C1 has a straight portion and a portion that is bent from the straight portion. When the radius of curvature of the curve C1 changes, it is preferable that the radius of curvature change continuously. The opposing line C2 is a curve (a parallel curve to the curve C1) that is located at a certain distance from each point on the curve C1 in the normal direction.

[0104] The radius of curvature of the curve C1 is not particularly limited. Hereinafter, the smallest radius of curvature among the radii of curvature of points on the curve C1 is referred to as the minimum radius of curvature. When the curve C1 is an arc of a perfect circle, the minimum radius of curvature is the same as the radius of the perfect circle. The minimum radius of curvature of the curve C1 is preferably 10 mm or more, more preferably 20 mm or more, and even more preferably 30 mm or more. From the viewpoint of favorably concentrating the magnetic flux density, the minimum radius of curvature of the curve C1 is preferably 100 mm or less, more preferably 75 mm or less, and even more preferably 50 mm or less. From these viewpoints, the minimum radius of curvature of the curve C1 is preferably 10 mm or more and 100 mm or less, more preferably 20 mm or more and 75 mm or less, and even more preferably 30 mm or more and 50 mm or less. When the curve C1 is an arc of a perfect circle, the central angle of the curve C1 is preferably 120° or more and 180° or less, more preferably 150° or less.

[0105] (5) Average Orientation of Magnet 111 Magnet 111 has an average orientation of 90% or more in each 1 mm wide portion 112 centered on a normal Nn at multiple points Pn from one end to the other end of curve C1 on the convex side in the second direction on the outer periphery of magnet 111 when viewed from the first direction. The average orientation can be, for example, 92% or more, 94% or more, 95% or more, or 96% or more. The higher the average orientation of magnet 111, the better, but it is usually 99.5% or less.

[0106] The method for measuring the average degree of orientation of magnet 111 will be described below with reference to Figures 16 and 18. The average degree of orientation of magnet 111 is determined as the average degree of orientation of each 1 mm wide portion centered on the normal Nn at multiple points Pn from one end to the other end of the convex curve C1 on the outer periphery of magnet 111 as viewed from the first direction (Z-axis direction). The number of multiple points Pn is not particularly limited. If the size of magnet 111 is sufficiently small, the number of multiple points Pn may be two, but five or more is preferable. The number of multiple points Pn is usually 10 or less.

[0107] First, as shown in FIG. 16, multiple points Pn are identified. In this embodiment, five points P1-P5 are identified. On the magnet 111, points P1 and P5 are taken at both ends of the curve C1 on the convex side, within 5 mm of one end (e.g., the left end) and within 5 mm of the other end (e.g., the right end). Multiple points (points P2-P4 in this embodiment) are taken in order from one end at positions that divide the distance between points P1 and P5 at both ends of the curve C1 into equal intervals (positions that divide the distance into four equal parts in this embodiment). Note that point P3 in this embodiment is located in the middle of the curve C1.

[0108] On the curve C1, the normal lines N1-N5 at each point P1-P5 are identified. 1 mm wide portions 112 are cut out from the magnet 111, centered on the normal line Nn. Each portion 112 is, for example, approximately rectangular prism-shaped, as shown in FIG. 18. In reality, the top and bottom surfaces of FIG. 18 are curved surfaces. The degree of orientation of each portion 112 is measured, for example, using a pulsed high magnetic field measuring device (magnetic field: 4 T). If the cut-out portion does not fit into the measuring device, a sample of a size that can fit into the measuring device is cut out from the center of the cut-out portion. The average value of the degrees of orientation of each portion 112 is calculated as the average degree of orientation.

[0109] The average degree of orientation of the magnet 111 in FIG. 17 can also be calculated using the same measurement method as above.

[0110] In addition, the magnet 111 can achieve the above average orientation degree of 90% or more by applying a magnetic field that spreads in the normal direction of the curve C1 of the magnet 111 in the orientation process described below, for example.

[0111] 2. Manufacturing Method of the Magnet Laminate 110 There are no particular limitations on the manufacturing method of the magnet laminate 110. An example of a manufacturing method of the magnet laminate 110 in which magnets 111 and insulating layers 113 are alternately stacked is shown below.

[0112] In the manufacturing method of the laminated magnet 110, the (1) SC alloy preparation step, (2) hydrogen crushing step, (3) coarse pulverization step, first lubricant addition step, (4) fine pulverization step, and second lubricant addition step are the same as the explanations of the (1) SC alloy preparation step, (2) hydrogen crushing step, (3) coarse pulverization step, first lubricant addition step, (4) fine pulverization step, and second lubricant addition step in "2. Manufacturing method of rare earth magnet 10" in the first embodiment, and this explanation applies as is.

[0113] (5) Powder Filling Process, Orientation Process, and Molding Process The SC alloy powder after the pulverization process is filled into a mold. This process is preferably performed, for example, under an inert atmosphere (such as a nitrogen atmosphere or an argon atmosphere). A mold having multiple molding spaces of a predetermined thickness is used. Each molding space is separated, for example, by multiple partition plates. A magnetic field is applied in a predetermined direction to the mold after powder filling to align the orientation of the SC alloy powder. For example, if the magnet 111 has an arc shape as shown in FIG. 16, a radial magnetic field (a magnetic field in which magnetic field lines radiate) is applied. The SC alloy powder filled into the mold is then compressed to form an SC alloy compact. In this way, an SC alloy compact having a predetermined degree of orientation (e.g., an average orientation of 90% or more) and a predetermined thickness (e.g., a thickness of 1.2 mm to 2.5 mm) can be obtained without a cutting process. The shape of the compact can be made as desired by changing the shape of the mold into which the SC alloy powder is filled after the pulverization process. In addition, the average degree of orientation of the compact can be increased by using an orientation coil that matches the shape of the compact.

[0114] In the manufacturing method of the magnet laminate 110, the (6) mold disassembly step, the first firing step, the (7) insulating layer application step, the (8) laminate temporary fixing step, and the (9) hot pressing step are the same as the explanations of the (6) mold disassembly step, the first firing step, the (7) insulating layer application step, the (8) laminate temporary fixing step, and the (9) hot pressing step in “2. Manufacturing method of rare earth magnet 10” in the first embodiment, and this explanation applies as is.

[0115] The magnet stack 110 obtained as described above can be understood as a magnet stack manufactured by hot pressing (hot uniaxial pressing) a laminate in which the raw material of the insulating layer 113 is sandwiched between at least a pair of magnets 111, 111 (sintered bodies of SC alloy), so that pressure is applied in a direction that crushes the raw material of the insulating layer 113. The magnet stack 110 can also be understood as a magnet stack manufactured by arranging a first magnet 111 (sintered body of SC alloy), the raw material of the insulating layer 113, and a second magnet 111 (sintered body of SC alloy) in this order to form a laminate, and applying pressure to the first magnet 111 and the second magnet 111 from both sides while heating the laminate. The raw material of the insulating layer 113 may further contain a component containing a heavy rare earth element. For example, the raw material of the insulating layer 113 may be CaF ２ and TbF ３ When the total of CaF is taken as 100 mass % ２ It is preferable that the content of TbF is 20 mass % to 40 mass %. ３ It is preferable that the content is 60 mass % to 80 mass %.

[0116] 3. Functions and Effects of the Present Embodiment The motor 130 of the present embodiment includes the magnet laminate 110, which improves performance in terms of suppressing thermal degradation, suppressing efficiency decline, and reducing magnet temperature. The reason for this is presumed to be as follows. Note that the present disclosure is not limited to this presumption. The magnet laminate 110 of the present embodiment is composed of multiple magnets 111 and insulating layers 113 stacked together, thereby reducing eddy current loss. On the other hand, when using magnets 111 with a convex curved shape as in the present embodiment for the magnet laminate 110, it is difficult to increase the average degree of orientation measured as described above. For example, high-voltage magnetic field pressing is generally considered to be an effective method for increasing the degree of orientation of magnets. However, high-voltage magnetic field pressing is limited to the production of large block magnets due to restrictions on the size and shape of the molding die. Therefore, high-voltage magnetic field pressing is not suitable for producing thin magnets such as those used in magnet laminates. Another approach under consideration is to parallel-align a rectangular magnet when viewed from a first direction, and then bend it so that it is convex in a second direction, thereby producing a magnet with a curved convex shape. However, bending a magnet reduces the degree of orientation of the magnet, and it is difficult to ensure a sufficient average degree of orientation when bent. The present inventors conducted extensive research to improve the average degree of orientation of the magnet 111, and developed the novel laminated magnet 110 of the present disclosure.

[0117] Since the laminated magnet 110 has an average degree of orientation of 90% or more, it is able to concentrate magnetic flux. Below, a computer simulation is used to examine the magnetic flux distribution of Sample A, Sample B, and Sample C when the magnets are applied to rotors. The finite element method electromagnetic field analysis software JMAG (manufactured by JSOL Corporation) was used to examine the magnetic flux distribution. The upper graphs of Figures 21 to 23 show the relationship between the angle in the range of a central angle of 90° in the rotor and the magnetic flux density. The magnets described below are used for each rotor. The horizontal axis represents the angle (°) with respect to the line OX shown in the rotor in the lower graph. The vertical axis represents the magnetic flux density (W / m ２ 21 to 23 show the rotor and the simulated distribution of magnetic flux density (absolute value). The arrows on each magnet roughly indicate the orientation direction of the magnet.

[0118] The magnets of Samples A, B, and C have the following properties: <Sample A> Shape of magnet when viewed from a first direction: rectangular Area of ​​main surface of magnet: 96.8 mm ２ (Long side dimension: 22 mm, short side dimension: 4.4 mm) Magnet orientation: Parallel orientation Average degree of magnet orientation: 97% Arrangement: Two magnets arranged in a V-shape. <Sample B> Magnet shape as viewed from the first direction: Arc shape (corresponding to a convex curved shape) Area of ​​the main surface of the magnet: 96.8 mm ２ (The radius of curvature of the outer arc was 25.4 mm, the radius of curvature of the inner arc was 21 mm, the outer and inner arcs were concentric, and both had a central angle of 54.3°) Magnet orientation: Parallel orientation Average degree of magnet orientation: 88% Arrangement: Two magnets were arranged in an arc shape. <Sample C> Magnet shape as viewed from the first direction: Arc shape (corresponding to a convex curved shape) Area of ​​the main surface of the magnet: 96.8 mm ２ (The radius of curvature of the outer arc is 25.4 mm, the radius of curvature of the inner arc is 21 mm, the outer arc and the inner arc are concentric, and both have a central angle of 54.3°) - Magnet orientation: Radial orientation - Average orientation degree of magnets: 95% - Arrangement: Two magnets were arranged in an arc shape.

[0119] The maximum magnetic flux density of sample A is 0.5388 W / m ２ The maximum magnetic flux density of sample B was 0.5521 W / m ２ The maximum magnetic flux density of sample C was 0.5729 W / m ２ Each magnetic flux density is rounded to the fifth decimal place.

[0120] Table 2 below summarizes the characteristics of "magnet shape," "average orientation," and "maximum magnetic flux density" for Sample A, Sample B, and Sample C. Each item is evaluated using the following criteria. Satisfaction of shape requirements: If the magnet shape is convexly curved, it is rated "satisfied," and if it is not convexly curved, it is rated "not satisfied." Satisfaction of orientation requirements: If the average orientation of the magnet measured using the above measurement method is 90% or more, it is rated "satisfied," and if it is less than 90%, it is rated "not satisfied." Table 2 shows that compared to Sample A, which uses a rectangular magnet (average orientation 97%, V-shaped arrangement), Sample B (average orientation 88%, arc-shaped arrangement) and Sample C (average orientation 95%, arc-shaped arrangement), which use convexly curved magnets, have high magnetic flux density despite their low average orientation. Furthermore, when comparing Sample B (average orientation 88%, arcuate arrangement) and Sample C (average orientation 95%, arcuate arrangement), both of which use convexly curved magnets, Sample C has a higher magnetic flux density than Sample B. From these results, it can be seen that the higher the average orientation of a convexly curved magnet, the more concentrated the magnetic flux density, thereby increasing the magnetic flux density. Therefore, it can be seen that a convexly curved magnet with an average orientation of 90% or more will have a higher magnetic flux density than a magnet with an average orientation of less than 90%. Sample B, which uses a convexly curved magnet, has a higher magnetic flux density than Sample A, which uses a rectangular magnet, even though it has an average orientation of 88%. Therefore, it can be seen that sufficient magnetic flux density can be achieved when the magnet is convexly curved and the average orientation is 90% or more.

[0121]

[0122] Furthermore, in the magnet laminate 110, the insulating layer 113 is primarily composed of inorganic crystals, so eddy current loss is unlikely to change. The reason for this is presumed to be as follows. However, the present disclosure is not limited to this presumption. The insulating layer 113, which is primarily composed of inorganic crystals, shows almost no change in resistance value in the range from room temperature (e.g., 25°C) to 150°C, so it is presumed that it is possible to reduce eddy current loss over a wide temperature range. Furthermore, since the insulating layer 113, which is primarily composed of inorganic crystals, has a thermal expansion coefficient close to that of the magnet 111, it is thought that the insulating layer 113 is unlikely to change in quality even through thermal cycling. Note that the difference in thermal expansion coefficient between the insulating layer 113 and the magnet 111 is ±3.0 x 10 －５ / K or less. For this reason as well, it is presumed that the durability (heat resistance) of the magnet laminate 110 of this embodiment is improved.

[0123] The magnet stack 110 of this embodiment has an insulating layer 113 between the magnets 111, 111. With this configuration, the insulating layer 113, which is primarily composed of inorganic crystals, can bond (adhere) the magnets 111, 111 with sufficient strength. Furthermore, because the insulating layer 113 is primarily composed of inorganic crystals, it can be made thinner while maintaining sufficient bonding strength compared to bonding layers made of resin or the like. Furthermore, if amorphous glass were used for the insulating layer, as opposed to this embodiment, there is a concern that the magnets may oxidize and lose their magnetic properties. On the other hand, because the insulating layer 113 of this embodiment is primarily composed of inorganic crystals, the magnetic properties of the magnets 111 can be suitably maintained. [Example]

[0124] The present disclosure will be explained in more detail below with reference to examples.

[0125] 1. Fabrication of Laminated Magnets <Experimental Examples 1C to 5C> (1) SC Alloy Preparation Step The main raw materials of an Nd / Pr alloy, an alloy containing Co, Al, Cu, Ga, and Zr, and a single metal were mixed to form a strip cast alloy (SC alloy) (for example, composition: Nd ２ Fe １４ B) was prepared under an argon atmosphere. The SC alloy was a plate-shaped powder with a main surface dimension of 10 mm × 10 mm to 20 mm × 20 mm.

[0126] (2) Hydrogen Crushing Step The SC alloy was allowed to absorb hydrogen in a hydrogen furnace (hydrogen atmosphere, 200°C, 2 hours) to embrittle the grain boundaries (neodymium-rich phases) of the SC alloy.

[0127] (3) Coarse grinding step, first lubricant addition step A lubricant was added to the SC alloy powder that had undergone the hydrogen crushing step. Methyl caprylate was used as the lubricant. The lubricant was mixed at a ratio of 0.03% by mass to 0.07% by mass relative to the amount of SC alloy. While adding the lubricant to the SC alloy powder, the powder was coarsely ground using a stirrer in a nitrogen or argon atmosphere. The average particle size of the SC alloy after coarse grinding was 50 μm to 500 μm.

[0128] (4) Fine pulverization step, second lubricant addition step The SC alloy powder after adding the lubricant was finely pulverized in a nitrogen atmosphere using a jet mill. The average particle size D50 after fine pulverization was 2.0 μm-3.5 μm. A lubricant was added to the SC alloy powder after fine pulverization. Methyl laurate was used as the lubricant. The mixing ratio of the lubricant to the amount of SC alloy was 0.05% by mass-0.1% by mass.

[0129] (5) Powder Filling Process, Orientation Process, and Compaction Process: The SC alloy powder after the pulverization process and the second lubricant addition process was filled into each molding space of a mold equipped with multiple partition plates in a nitrogen atmosphere. Each compact formed in each molding space corresponds to each magnet to be stacked in a subsequent process. In the samples of Experimental Examples 1C to 5C, the thickness of each magnet was 2 mm. The planar shape of each magnet was an arc shape with a central angle of 180°, with the curve C1 having a radius of curvature of 15 mm and the opposing line C2 having a radius of curvature of 12 mm, and the curve C1 and opposing line C2 being concentric. A magnetic field (e.g., 5000 V) was applied to the mold after powder filling in the planar direction of each compact (perpendicular to the thickness direction) to align the orientation of the SC alloy powder. A radial magnetic field (a magnetic field in which magnetic lines of force radiate) was used. The SC alloy powder filled in the mold was compressed to form an SC alloy compact. The pressure molding conditions were: pressure: 5 MPa-20 MPa, packing density: 3.0 g / cm ３ -4.0 g / cm ３ , relative density: 40%-52%.

[0130] (6) Mold Disassembly Process, First Firing Process The outer frame was removed from the mold, and a continuous arrangement of molded bodies and partition plates (the object to be fired) was prepared. For dehydrogenation, the object to be fired (with the partition plates) was heated at 500°C for 3-4 hours in an Ar atmosphere. Thereafter, the object to be fired (with the partition plates) was held at 930°C-1050°C for 3 hours and fired in a vacuum atmosphere.

[0131] (7) Insulating Layer Coating Step After the first firing step, the partition plates were removed from the magnets to be fired, and the raw material for the insulating layer was coated on six surfaces of the magnets before lamination. The raw material for the insulating layer consisted of the compound powders of the main components listed in Table 3 and TbF ３ The compound powder and the solvent were mixed. ３ The ratio of the compound powder was 10 mass % to 20 mass %. The thickness of the insulating layer raw material was 12 μm or more and 14 μm or less. The insulating layer raw material was applied in the air by a spray method.

[0132] (8) Laminate Temporarily Fixing Process 25 magnets coated with an insulating layer were stacked in air and temporarily fixed. The number of magnets stacked was adjusted so that the dimension of the laminated magnet in the stacking direction was 50 mm. This method allows for the production of plate-shaped magnets without the need for a cutting process or other process to cut out plate-shaped magnets from a larger magnet.

[0133] (9) Hot Pressing Step The temporarily fixed laminate was placed in a hot press mold and subjected to uniaxial hot pressing. This step was carried out under a vacuum atmosphere (for example, 10 －３ Pa-10 －４ The hot pressing was carried out in a 1000 psi (1000 Pa) or in an inert atmosphere (nitrogen atmosphere, argon atmosphere). The hot pressing temperature was 700°C to 1100°C, the hot pressing time was 1 second to 1 hour, the hot pressing pressure was 3 MPa to 100 MPa, and the hot pressing heat treatment time was 10 minutes to 20 hours. In this manner, laminated magnet samples for Experimental Examples 1C to 5C were produced.

[0134] Experimental Example 1D: In Experimental Example 1D, the insulating layer coating step and the pressing step described below were performed instead of the insulating layer coating step (7) and the hot pressing step (9). The steps other than the insulating layer coating step and the pressing step described below were the same as the steps (1)-(6) and (8) described above for Experimental Examples 1C to 5C, and a laminated magnet sample for Experimental Example 1D was produced.

[0135] In Experimental Example 1D, in the insulating layer coating step, first, TbF ３ The mixture of the compound powder and solvent was applied to the surface. The surface was then heat treated until the coating was completely removed. After that, epoxy resin was applied.

[0136] In Experimental Example 1D, in the pressing step, the temporarily fixed laminate was placed in a press mold and pressed uniaxially. This step was carried out in an air atmosphere. The pressing temperature was 25°C, the pressing time was equal to or longer than the time required for the resin to harden, and the pressing pressure was 3 MPa.

[0137] Experimental Example 2D: Experimental Example 2D was not a laminated magnet, but a single magnet with a thickness of 50 mm. The planar shape of the magnet was an arc shape with a central angle of 180°, with the curve C1 having a radius of curvature of 15 mm, the opposing line C2 having a radius of curvature of 12 mm, and the curve C1 and opposing line C2 being concentric, similar to Experimental Examples 1C to 5C. Except for the magnet thickness being 50 mm, the same (1) SC alloy preparation step, (2) hydrogen decomposition step, (3) coarse pulverization step, first lubricant addition step, (4) fine pulverization step, second lubricant addition step, (5) powder filling step, orientation step, and molding step were performed as in Experimental Examples 1C to 5C. The resulting compact was a block with no partition plate interposed between them. As the demolding step and first firing step of Experimental Example 2D, the outer frame was removed from the mold, and a compact (object to be fired) was prepared. The magnet was then heated and fired for dehydrogenation under the same conditions as in the (6) mold disassembly step and first firing step described above. After the first firing step, the insulating layer material was applied to six surfaces of the magnet of Experimental Example 2D. The insulating layer material and the thickness of the applied insulating layer material were the same as in Experimental Examples 1C to 5C. The magnet with the insulating layer material applied was placed in a hot press mold and subjected to uniaxial hot pressing as in Experimental Examples 1C to 5C.

[0138] <Experimental Example 3D> In Experimental Example 3D, a sample of the laminated magnet of Experimental Example 3D was produced in the same manner as in the above steps (1)-(4) and (6)-(8), except that a parallel magnetic field was applied instead of a radial magnetic field in the above (5) powder filling step, orientation step, and molding step.

[0139] <Experimental Example 4D> In Experimental Example 4D, the planar shape of the magnets was not an arc shape, but a 5 mm x 16 mm rectangle. Each magnet was a rectangular parallelepiped with dimensions of 2 mm thick x 5 mm x 16 mm. Other than the rectangular shape of the magnets, the same processes as Experimental Examples 1C to 5C were carried out: (1) SC alloy preparation step, (2) hydrogen crushing step, (3) coarse crushing step, first lubricant addition step, (4) fine crushing step, and second lubricant addition step. In Experimental Example 4D, a laminated magnet sample was produced in the same manner as in the above steps (6) to (8), except that a parallel magnetic field along the short side of the rectangle was applied instead of a radial magnetic field in the above (5) powder filling step, orientation step, and compaction step.

[0140] 2. Characteristics of Experimental Examples 1C to 5C and Experimental Examples 1D to 4D Table 2 summarizes the characteristics of the magnets and insulating layers of Experimental Examples 1C to 5C and Experimental Examples 1D to 4D. The "Type" column of "Magnet" indicates the type of magnet. "Neodymium magnet" means Nd ２ Fe １４ This indicates that the magnet has B as its main phase. The "Shape" column shows the shape of the magnet when viewed from a first direction. The "Insulating Layer" column shows the compound contained in the insulating layer in the largest amount (mass %). Regarding the components of the insulating layer, inorganic substances were identified using EPMA and XRD, and organic substances were identified using NMR and IR analysis. The "Number of Divisions" column shows the number of divisions of the laminated magnet, i.e., the number of layers of the magnet. Since Experimental Example 2D is an undivided magnet, the number of divisions was set to "0". The "Average Orientation" column shows the average orientation measured using the method described in the embodiment.

[0141]

[0142] 3. Performance Evaluation (1) Method for Evaluating Magnet Temperature The magnets of Experimental Examples 1C to 5C and Experimental Examples 1D to 4D were each attached to a motor, and a test was conducted in which the motor was driven for 0.5 hours at a maximum torque of 500 N m and a maximum rotational speed of 10,000 rpm. Immediately after the test, the surface of the magnets of Experimental Examples 1C to 5C and Experimental Examples 1D to 4D was observed with a laser, and the surface temperature (°C) was measured.

[0143] (2) Method for Evaluating Magnet Temperature After 200 Hours of Operation Each motor that had undergone "(1) Method for Evaluating Magnet Temperature" was further tested by operating it for 200 hours at a maximum torque of 500 N m and a maximum rotational speed of 10,000 rpm. Immediately after the test, the surface of the magnet of each of Experimental Examples 1C to 5C and Experimental Examples 1D to 4D was observed with a laser to measure the surface temperature (°C). The surface temperature after 0.5 hours of operation was set as 100%, and the rate of change (%) in the surface temperature of the laminated magnet of Experimental Examples 1C to 5C and Experimental Examples 1D, 3D, and 4D was calculated. A small rate of change (%) is an indicator that temperature rise is suppressed and thermal degradation is less likely to occur. Rate of change (%) = (T ２００ -T ０．５ ) / T ０．５ x100 T ０．５ T: Surface temperature after 0.5 hours of operation (°C) ２００ : Surface temperature after 200 hours of operation (°C)

[0144] The evaluation was made as follows: Magnet temperature (change after 200 hours) "A": rate of change 10% or less "B": rate of change greater than 10%

[0145] (3) Method of Evaluating Efficiency Region For the motors equipped with the magnets of Experimental Examples 1C to 5C and Experimental Examples 1D to 4D, a graph of rotation speed-torque characteristics was obtained, with the horizontal axis representing rotation speed (rpm) and the vertical axis representing torque (N m). Motor efficiency is expressed as the ratio of the output (W) from the motor to the input power (W) input to the motor. Motor efficiency (%) can be calculated using the following formulas: Motor efficiency (%) = (output (W) / input power (W)) x 100 Output (W) = 2π x rotation speed (s －１ ) x torque (N m) 1 (rpm) = 1 / 60 (s －１ )

[0146] In the graph of the rotational speed-torque characteristics of the motors described above, the area of ​​the high-efficiency region where the motor efficiency is 90% or higher was calculated. The area A1 of the high-efficiency region of the motor of Experimental Example 2D was set to 100%, and the rate of change (%) of the area As of the high-efficiency region of the motors of Experimental Examples 1C to 5C and Experimental Examples 1D, 3D, and 4D was calculated. A large rate of change (%) indicates that the area of ​​the high-efficiency region is large and that a decrease in motor efficiency is suppressed. Rate of change (%) = (As - A1) / A1 x 100 A1: Area of ​​the high-efficiency region of the motor of Experimental Example 2D As: Area of ​​the high-efficiency region of the motors of Experimental Examples 1C to 5C and Experimental Examples 1D, 3D, and 4D

[0147] The evaluation was made as follows: Efficiency range "A": rate of change 5% or more "B": rate of change less than 5%

[0148] 4. Evaluation Results The evaluation results are also shown in Table 3. Experimental Examples 1C to 5C satisfy the following requirements (a) to (d). In contrast, Experimental Example 1D does not satisfy the following requirement (d). Experimental Example 2D does not satisfy the following requirement (a). Experimental Example 3D does not satisfy the following requirement (c). Experimental Example 4D does not satisfy the following requirement (b). Requirement (a): The laminated magnet has multiple magnets and insulating layers stacked in a first direction. Requirement (b): The magnets contain a rare earth element and have a curved shape that is convex in a second direction when viewed from the first direction. Requirement (c): The average degree of orientation of each 1 mm wide portion centered on the normal line at multiple points from one end to the other end of the curve on the convex side in the second direction on the outer periphery of the magnet when viewed from the first direction is 90% or more. Requirement (d): The insulating layer is primarily composed of inorganic crystals.

[0149] Experimental Examples 1C to 5C were rated "A" for magnet temperature after 200 hours of operation. Experimental Examples 1C to 5C were rated "A" for efficiency area. In contrast, Experimental Example 1D was rated "B" for magnet temperature after 200 hours of operation and "B" for efficiency area. Experimental Examples 2D and 3D were rated "B" for efficiency area. It was suggested that Experimental Examples 1C to 5C can reduce eddy current loss generated internally and can achieve any one of the following effects: suppression of thermal degradation, suppression of efficiency decline, and reduction of magnet temperature by concentrating magnetic flux. Such motors are considered to be useful in high-speed rotation motors used in high rotation speed ranges (e.g., rotation speeds of 7,500 rpm or more).

[0150] 5. Effects of Examples Experimental Examples 1C to 5C were able to improve any of the performances related to suppression of thermal degradation, suppression of efficiency decline, and reduction of magnet temperature.

[0151] The present invention is not limited to the above-described embodiments, and various modifications and variations are possible within the scope of the claims of the present invention.

[0152] <Explanation of symbols in the description of the first embodiment> 10... rare earth magnet 11... magnet 13... insulating layer 30... motor 31... stator 33... rotor 34... rotating shaft 35... rotating core 37... shaft hole 39... magnet hole <Explanation of symbols in the description of the second embodiment> 110... laminated magnet 111... magnet 113... insulating layer 130... motor 131... stator 133... rotor 134... rotating shaft 135... rotating core 137... shaft hole 139... magnet hole

Claims

1. A motor equipped with a laminated magnet, the laminated magnet having a plurality of magnets and an insulating layer present between the plurality of magnets, the insulating layer being primarily composed of inorganic crystals.

2. The motor described in claim 1, wherein the laminated magnet is formed by stacking the multiple magnets and the insulating layer in a first direction, the magnet contains a rare earth element and has a curved shape that is convex in a second direction when viewed from the first direction, and the average orientation of each portion of a 1 mm width centered on a normal line at multiple points from one end to the other end on the curve on the convex side in the second direction on the outer periphery of the magnet when viewed from the first direction is 90% or more.

3. The motor according to claim 1 or 2, which is used at a maximum rotational speed of 7,500 rpm or more.

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